1- iscsi security.pdf

iSCSI Security
(Insecure SCSI)
Presenter:
Himanshu Dwivedi

www.isecpartners.com
Agenda
• Introduction
• iSCSI Attacks
– Enumeration
– Authorization
– Authentication
• iSCSI Defenses

Information Security Partners (iSEC)
• iSEC Partners
– Independent security consulting and product organization
• Our Focus
– Application Security
• Java, C++ and .NET applications
• Attacking Web Services (XML, SOAP) – Alex Stamos and Scott Stender
– Network Security
• Firewalls, Routers/Switches, VPNs, and Operating Systems
– Storage Security
• NAS, iSCSI, and SANs
– Product Security
• Software Applications (home grown and commercial off-the shelf)
• Hardware Appliances (devices)
• For more information
– https://www.isecpartners.com

Introduction
• iSCSI
i = Internet Protocol
SCSI = Small Computer System Interface
iSCSI = Insecure SCSI
• What is iSCSI?
– iSCSI (Internet Small Computer Systems Interface) provides access to
block level data over traditional IP networks
– SCSI blocks have mostly been used with Fibre Channel SANs
– Unlike NAS storage devices using CIFS/NFS at the file level, SCSI blocks
work at lower levels by offering entire data stores (LUNs) to iSCSI clients

Introduction
• Block level vs. File level
– File Level: CIFS (SMB) and NFS file systems over a network connection
– Block Level: The actually drive (not the file system) over a network
– Simplistic example: A file system versus an entire hard drive
• Security and iSCSI
– Authentication – CHAP (weak)
– Authorization – Initiator Node Names (spoof-able)
– Encryption – IPSec shared secret (deployment challenges)
• Why should we care?
– A compromise of a single iSCSI device equates to the compromise of several (10 to
100) operating systems at once!
• Who cares about admin, root, or system accounts when the entire data store can
be compromised?

Introduction
• What *some* vendors say about iSCSI Security
• Implies trusting everyone (employees, vendors, business partners, guests,
contractors, consultants, wireless users, and remote VPN users) that is
connected to the internal network
Agree to…..
- Remove all file permissions from all folders in every operating system
- Allow everyone to read everyone else's email
- Remove all passwords from databases
- Allow everyone to view HR information (Soc Sec Numbers, Salaries)
- Tell the Auditors that “Internal controls are for sissies”

Introduction
• iSCSI Architecture Components
– iSCSI Initiator: An iSCSI client
– iSCSI Target: An iSCSI storage device/appliance
– iSNS (optional): iSCSI Name Services (A table that groups iSCSI
Initiators and Targets in Domain Sets for logical
segmentation
• Terms and Definitions
– iQN: Initiator Node Name (Identity value for iSCSI clients,
similar to MAC addresses)
– Domain Sets: Logical segmentation of iSCSI entities (Targets and
Initiators into separate groups)
– LUNs: Logical Unit Numbers (A logical array of storage
units. One storage entity can be divided into
multiple LUNs)

Introduction
• iSCSI Initiators
– iSCSI Clients
– Use a regular NIC (IP) with an iSCSI client driver
• iSCSI Drivers
– Microsoft
– Cisco
– IBM
– HP
• NO special hardware required
• Works over existing IP networks
iSCSI Driver

Introduction
• iSCSI Targets
– iSCSI Devices (Appliances)/Servers
– Offer large volumes of data (block level) over the IP network
• iSCSI Vendors
– Cisco
– EMC
– Network Appliance
– HP
– IBM
• Listens on TCP port 3260
iSCSI Device

Introduction
• Example iSCSI Architecture
Network LUN =
Local =
LUN 1
LUN 2
LUN 3
LUN 4
iSCSI Connection
iqn.1991-05.com.Microsoft:123
iqn.1987-05.com.cisco:456

Introduction
• iSCSI allows block data to be available over the IP network
Network
Local
Operating System
(iSCSI Initiator)
iSCSI Device
(iSCSI Target)

OS
Introduction
• iSNS Servers (iSCSI Simple Name Services)
– Software that runs on an operating system or an iSCSI Device
– iSCSI initiators and targets register with the iSNS server
• Similar to DNS
– An iSNS server is responsible for:
• Informing iSCSI clients about which iSCSI targets are available on the network
• Grouping iSCSI clients to their correct Domain Set
• Informing iSCSI clients what security aspects (if any) they must use to
associate to targets
– Listens on port TCP 3205.
iSCSI Device
iSNS Server

Introduction
• iSNS Model
XYZ iSCSI Storage Device
iSCSI Client iSNS Server
123 iSCSI Storage Device
iSNS Registration
Available iSCSI Targets….for your Domain Set
iqn.1987-05.com.XYZ:111773
Query iSNS information
iqn.1991-05.com.microsoft:win2003
Exchange Domain
iqn.1991-05.com.microsoft:win2004-hd
iqn.1992-08.com.123:112699
Default Domain Set
iqn.1987-05.com.XYZ:111773
iSNS
Registration
iqn.1987-05.com
.XYZ:111773

Introduction
• iSNS Example

Introduction
Top 5 iSCSI Security Issues
1. iQN Values are trusted
a. iQN are spoof-able, sniff-able, and can be brute-forced
2. iSCSI Authorization is the only required security entity,
which relies on iQN values
3. iSCSI Authentication is disabled by default
4. iSCSI Authentication uses CHAP
5. iSNS servers are not protected
iSCSI is a clear text protocol

iSCSI Enumeration

iSCSI Enumeration
• Scanning iSCSI Targets (Devices)
– TCP port 3260 and 3205
– StorScan is a focused port scanner for storage devices
• iSCSI SANs and IP NAS
• Yes. Nmap is much better, but StorScan is focused (filtered)
– storscan.exe <range>

iSCSI Enumeration
• Enumeration
– iSCSI Targets (iSCSI Devices)
• Listen on TCP port 3260
– iSNS
• Listen on TCP port 3205
– iSCSI Clients
• Do not listen on a port, but can be enumerated from the iSNS server

iSCSI Enumeration
• iSNS registration
– If unique Domain Sets are not created,
each iqn will be placed in the Default
Domain Set.
– Any member of a domain set will be
able to enumerate/access the other
nodes in the same domain set
• This is why it is important to move
nodes out of the Default Domain Set
– Foo can
1. Scan for port 3205 and find a iSNS
server
2. Connect to the iSNS server
3. Enumerate the other iSCSI nodes,
which can now be used for iqn spoofing
attacks (described later)

iSCSI Enumeration
• iSNS Man-in-the-Middle
– Identify iSNS server on port 3205
– Using layer 2 ARP poisoning attacks, a fake iSNS server can
replace the real iSNS server
• The real iSNS will continue to receive iSNS information from
targets and clients, but after the fake iSNS has control of the
packets
• This allows the fake iSNS server to
– View all registrations (both targets and clients)
– Modify or change Domain Sets
– Downgrade Domain Sets that require security
(remove authentication or encryption)

iSCSI Enumeration
• iSNS MITM
iSCSI Client
Real iSNS Server
iSCSI Target
Capture iQNs
Modify Domain Sets
Modify Security Requirements
Fake iSNS Server

iSCSI Authorization

iSCSI Authorization
• iSCSI
– Authorization (Required)
• Required iSCSI Security component
• Initiator Node Name
– Only unknown variable is the end string
» iqn.1991-05.com.microsoft:HOSTNAME
» iqn.1987-05.com.cisco:xxxxxx
» iqn.1992-08.com.ibm:<partition identifier>
– iQNs traverse the network in CLEAR-TEXT
» Easily sniffable, guessable, or enumerated
• An attacker can get access to large amounts of data with little effort

iSCSI Authorization
• iSCSI Authorization Attack
– Sniff iSCSI Communication
• Port 3260
• Get Initiator Node Names
– Spoof the Initiator Node Name
• Change Initiator name with iSCSI driver
– See Data
• Gain access to confidential and sensitive data

iSCSI Security
• iSCSI Attack Demo
iSCSI Storage Device
Trusted
iSCSI Client
Malicious
iSCSI Client
IP Switch
LUN 0001 LUN 0002
Trusted Client has
access to LUN 0001
iqn.1991-05.com.microsoft:win2003-hd = LUN 0001
iqn.1991-05.com.microsoft:jum4nj1
Malicious client will perform
three steps to get access to
trusted data:
1. Sniff
2. Spoof
3. See Data

iSCSI Security
LUN 0005
LUN 0004
LUN 0003
LUN 0002
Trusted
iSCSI Client
Malicious
iSCSI Client
IP Switch
LUN 0001
LUN 0010
LUN 0009
LUN 0008
LUN 0007
LUN 0006
Trusted Client has
access to LUN 0001,
0002, 0003, 0004, and
0005
iqn.1987-05.com.cisco:01.1e2d66bf412c
iqn.1987-05.com.cisco:01.1e2d66bf412 = LUN 0001 thru LUN 0005
Malicious client will perform
three steps to get access to
trusted data:
1. Sniff
2. Spoof
3. See Data
iqn.1987-05.com.cisco:01.1e2d66bf412c

iSNS Domain Hopping
• iSNS Domain (iGroup) Hopping
– Similar to VLAN hopping and Zone hopping (Fibre channel)
– Discovery Domains/iGroups rely on the iQN value of a node
for identification
– If a node simply spoofs the iQN value to match the iQN of
their target, the iSNS server will automatically update and
overwrite the legitimate node’s information with the
attacker’s spoofed information
• Domain/iGroup Damage:
– At a minimum, this is a Denial of Service Attack
– At a maximum, this would allow unauthorized hosts to
access targets (and their data LUNs) in restricted domains

iSNS Domain Hopping
• iSNS Domain Hopping
iSNS Registration
Trusted Domain Entity
iqn.1991-05.com.microsoft:win2003 win2003
Default Domain Set Entity
iqn.1991-05.com.microsoft:isec isec
iSNS
Registration
iqn.1991-05.com
.m
icrosoft:isec
iqn.1991-05.com
.m
icrosoft:win2003
iqn.1991-05.com.microsoft:win2003 isec
Win2003
isec
iqn.1991-05.com.aum:iscsi iscsi

iSNS Domain Hopping
After…
Before …

iSCSI Authentication

• iSCSI Security
– Authentication: Optional Security
• Optional iSCSI Security component
– Authentication (CHAP)
– Vulnerable to several attack types:
» Sniffing of usernames
» Off-line brute force attack of secret (password)
» Message reflection attack

iSCSI Client
Attacker
Auth Request
CHAP ID and Message Challenge
CHAP_I= 194
CHAP_C= e500370b
(ID + secret +challege)MD5 = Hash (CHAP_R)
CHAP Hash
CHAP_R = c0d749fd2be1226c891e3c21d45016cd
ID (CHAP_I) = 194
Challenge (CHAP_C) = e500370b
Secret = ???????
Hash (CHAP_R) = c0d749fd2be1226c891e3c21d45016cd
(194 + secret + e500370b) MD5 =
c0d749fd2be1226c891e3c21d45016cd
(194 + secret + e500370b) MD5 =
c0d749fd2be1226c891e3c21d45016cd

• iSCSI Authentication Attack
– CHAP: (ID + secret +challege)MD5 = Hash (CHAP_R)
• Sample: (1 + x + 5)/2 = 5
• Sample: (1 + 1 + 5)/2 != 5
• Sample: (1 + 2 + 5)/2 != 5
• Sample: (1 + 3 + 5)/2 != 5
• Sample: (1 + 4 + 5)/2 = 5
– Sniff iSCSI Communication
• Sniff port 3260
• Obtain
– CHAP Username (CHAP_N)
– CHAP ID (CHAP_I)
– CHAP Message Challenge (CHAP_C)
– Resulting Hash (CHAP_R)
– Brute-force passwords (secret)
• Off line dictionary attack of every English word
– Compromise the secret (password)
• After two hashes match, the password is compromised

iSCSI Authentication: Offline Dictionary Attack
iSCSI CHAP Password Tester …
(www.isecpartners.com/tools.html)

Sniffed (Captured) Entities:
- ID (CHAP_I): 194
- Message Challenge (CHAP_C): e500370b
- Secret: ??????
- Hash (CHAP_R): c0d749fd2be1226c891e3c21d45016cd
(ID + Dictionary Word + Message Challenge) MD5 = Hash
194 Hello e500370b 81d0c90ad83d06bf0f51ce944f9c0341
194 My e500370b 2db5f956905e85e6fd242a54d9213e9a
194 Name e500370b 08dd57f2fcb535ae6c3d32716d54c97c
194 Is e500370b bc7329be2a9fa99fa596802b6a00424d
194 Kusum e500370b 13ec91aeb5ea120e971a29ad0e2d0e86
194 And e500370b 0708568450c40b67fc885e6685579cc4
194 Voice e500370b 28b255f4e1ecbe44e8c7827d039b523e
194 Is e500370b bc7329be2a9fa99fa596802b6a00424d
194 Passport e500370b 4983811b661e3d1dfda16a1c39f2b201
194 Verify e500370b 629c2a938740d0332042b486db58b8dd
194 Me e500370b efb2712166bfafe7fcf6b3c0f0cf60d3
194 iscsisecurity e500370b c0d749fd2be1226c891e3c21d45016cd
Actual Secret: iscsisecurity

iSCSI CHAP Password Tester:

• Message Reflection Attacks
– Reflection of a CHAP message challenge across multiple connections
• Overview
– An attacker (iSCSI client) would request authentication to a iSCSI target
• The client receives the CHAP ID and Challenge
– Since the attacker does not know the secret (password), it cannot formulate the correct
MD5 hash. However, the attacker can open a completely separate connection to the
target (connection number 2) and force the Target to authenticate to it
• The RFC states that any iSCSI target must response to authentication requests be default!
– The Target receives the same ID and Challenge it just sent to the client (but in a
different connection) and also knows the correct secret. The target will formulate the
correct MD5 hash and pass it back, as if it were trying to authenticate to the client
– This essentially gives the attacker (the client) the correct MD5 hash to authenticate in
the iSCSI Target in the first connection!

• Message Reflection
iSCSI Client
(Attacker)
Auth Request
CHAP_I= 194
CHAP_C= e500370b
CHAP Hash
(194 + secret + e500370b) MD5 =
c0d749fd2be1226c891e3c21d45016cd
CHAP_I= 194
CHAP_C= e500370b
CHAP Hash
!!!
Connection 1
Connection 2

iSCSI Petty Problems

• Microsoft iSCSI Client
– Driver logs iSCSI secrets (passwords) that don’t conform to the correct size
in the clear in the Event Viewer

– The client’s CHAP secret is protected with ‘darkened circles’ but can be
revealed with a box revealer

– The client’s IPSec key is protected with ‘darkened circles’ but can be
revealed with a box revealer

iSCSI Defenses

iSCSI Defenses
• How to defend against these threats?
– CONFIGURATION, CONFIGURATION, CONFIGURATION
– Every iSCSI device should be secured just like an other operating system or
application
• Pay no attention to the man behind the curtain!
– Audit your iSCSI storage devices/networks and assess the risk!
• STORAGE need your security loving too!!!
– iSCSI storage devices, which hold your DATA, are similar to everything else
on the network….
• Vulnerable to attacks
• Security holes and weaknesses
• Need to be protected and secured

iSCSI Defenses
Top 10 iSCSI Security Recommendations
• Specific configurations
1. Enable Mutual Authentication
• Do not rely solely CHAP Auth
2. Create Multiple Discover Domains
• Only use the Default Domain Sets for random registrations
3. Enable CRC checksums for integrity checking
4. Require iSNS IPSec (where possible)
5. Do not only rely on iQNs for security authorization values
6. Enable iSCSI IPSec (where possible)
• Vendors!
7. Incorporate Kerberos
8. Enable authentication by default
9. Support iSNS authenticated heartbeats before registrations
10. Support iSNS security features in the RFC

Questions
Himanshu Dwivedi
Himanshu Dwivedi
•
• hdwivedi@isecpartners.com
hdwivedi@isecpartners.com or
or hdwivedi@lokmail.com
hdwivedi@lokmail.com
Security Books Authored by presenter:
Security Books Authored by presenter:
•
• Securing Storage
Securing Storage
•
•Publish date: Fall 2005
Publish date: Fall 2005

1- iscsi security.pdf

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